Ruby 块中奇怪的不完美之处
# This works
method :argument do
other_method
end
# This does not
method :argument {
other_method
}
为什么？
解释器似乎很困惑，并认为 { ... } 是一个散列。
当解释器无法理解实际有效的代码时，我总是很生气。它与 PHP 类似，也有很多此类问题。
Possible Duplicate:
What is the difference or value of these block coding styles in Ruby?
# This works
method :argument do
other_method
end
# This does not
method :argument {
other_method
}
Why?
It seems like the interpreter is confused and thinks that the { ... } is a hash.
I always get angry when an interpreter can't understand a code that is actually valid. It resembles PHP that had many problems of this kind.
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它不认为这是一个哈希 - 这是一个优先级问题。
{}绑定比do end更紧密，因此method :argument { other_method }被解析为method(:argument {other_method})，这在语法上是无效的（但如果参数不是符号而是另一个方法调用，那就是有效的）。如果添加括号 (
method(:argument) { other_method })，它将正常工作。不，该代码实际上并不有效。如果是的话，那就行了。
It doesn't think it's a hash - it's a precedence issue.
{}binds tighter thando end, somethod :argument { other_method }is parsed asmethod(:argument {other_method}), which is not syntactically valid (but it would be if instead of a symbol the argument would be another method call).If you add parentheses (
method(:argument) { other_method }), it will work fine.And no, the code is not actually valid. If it were, it would work.